Science and Technology Daily (Reporter Zhao Hanbin) Accidental ingestion of poisonous mushrooms causes death, but at the same time they are also a source of important drugs and functional molecules. Researchers at the Kunming Institute of Botany, Chinese Academy of Sciences, recently made important progress in deciphering the mechanism of gooseberry cyclopeptide toxin synthesis, and the results were published in full in the Proceedings of the National Academy of Sciences.
”In life, the vast majority of accidental poisoning deaths are triggered by gooseberry fungi, whose toxin is gooseberry cyclopeptide, but gooseberry cyclopeptide toxin is not unique to gooseberry fungi.” The paper’s first author and co-corresponding author, Luo Hong, an associate researcher at the Kunming Institute of Botany, introduced that this type of toxin can also be produced in mushrooms of the genera Cyclopeptide and Helicoverpa armigera, which are distantly related to goosefoot fungi.
The study by Hong Luo et al. identified two new key genes associated with the synthesis of gooseberry cyclopeptide toxin, both of which are different oxygenases responsible for introducing oxygen atoms at key sites of gooseberry cyclopeptide toxin. In the absence of these oxygen atoms, the activity of the toxin would be reduced more than 1000-fold. This discovery increases the number of known toxin synthesis genes from two to four, providing a deeper understanding of the biogenic synthesis pathway of goose paste cyclopeptide toxin.
By establishing the world’s only highly toxic gooseberry genome platform, the research team constructed genomic databases of 13 highly toxic species in the genera Gooseberry, Helicoverpa armigera, and Cyclops mushroom, and completely resolved the overall structure of the gooseberry cyclopeptide toxin biogenesis synthesis pathway in the Mushroom order. They found that the genetic basis for the production of gooseberry cyclopeptide toxin was consistent in these three genera, all controlled by similar genes.
Surprisingly, however, the ability to synthesize toxins in the three genera of mushrooms has varied widely over the evolutionary long run. In the wood-rotting Helicoverpa spp. fungi, there is only one toxin precursor gene; in the soil-rotting Cyclops fungi, there are about 10 toxin precursor genes; while in the mycorrhizal symbiotic Goosefoot fungi, the MSDIN precursor gene family has expanded significantly, and even new toxin modification genes have been produced that can expand the number of cyclic peptides tens of times, so that the actual toxin-producing capacity of Goosefoot fungi is tens of thousands of that of Helicoverpa and Cyclops fungi by thousands of times.
”Probably influenced by different physiological and ecological pressures, each of the three evolved in different directions, eventually forming very different fates.” Luo Hong said the goosefoot fungus is one of the best, with its goosefoot cyclopeptide toxin biogenesis pathway producing numerous innovations and a huge increase in toxicity, making it the “most toxic mushroom”.
